A conventional magazine 90 for receiving nails of nail guns is shown in FIG. 7 and generally includes an cover 91 and first rails 900 and second rails 901 defined in the magazine 90. A nail pusher 92 is slidable along the first or second rails 900, 901. A plurality of positioning portions 902 are defined in the magazine 90 so as to guide the separation plate 93 on the desired positioning portion 902 for accommodating nails of different sizes. The nails are then correctly pushed by the nail pusher toward the nose of the nail gun. When adjusting the position of the separation plate 3, the user has to remove the cover 91 from the magazine 90 and the separation plate 93 can be pulled out from the magazine 90 and then inserted in to the magazine 90 to set another space for receiving the nails of different size. There are many steps involved to remove the cover 91 and to re-install the separation plate 93. Therefore, the adjustment is a time-consuming task. Although some nail gun companies develop an adjustable device for adjusting the space for different nails of different sizes, the device is so complicated and is not satisfied in quality.
The present invention intends to provide an adjustable device which includes a control member on an outside of the magazine and the control member is connected with a bar which can be moved in the magazine to adjust the space into different sizes by rotating the control member.